Variable mesh low mass MEMS mirrors

ABSTRACT

The present disclosure provides a component, such as a MEMS mirror or other generally disc-shaped component, having a variable mesh pattern across a backside surface thereof. The variable mesh includes ribs having a first thickness near a center portion or axis of rotation of the components, and a second narrower thickness at portions farther from the center or axis of rotation.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of the filing date of U.S.Provisional Patent Application No. 62/976,814 filed Feb. 14, 2020, thedisclosure of which is hereby incorporated herein by reference.

BACKGROUND

Optical communications use modulated light beams to convey informationthrough optical fibers, free space, or waveguides. A beam of light canbe modulated either directly by modulating current to a light source, orexternally by using an optical modulator to modulate a continuous-wavelight beam produced by the light source. External modulation hasadvantages in that it can handle higher power and frequencies; however,the required components can be larger, more complex, and more expensive.

An optical circuit switch (OCS) is an all-optical, 3D switching matrixthat can direct light from any input fiber N to any output fiber M bychanging the angles of the mirrors in two 2D micro-electromechanicalsystem (MEMS) mirror arrays. The switch is designed for low insertionloss over a broad wavelength range, so each fiber can carry manywavelengths. The OCS is also designed for fast, reliable switching bythe MEMS mirror arrays. Optical performance requirements includeinsertion loss, return loss, dynamic optical crosstalk, and staticoptical crosstalk.

SUMMARY

One aspect of the disclosure provides a component, including a regionhaving a perimeter and a first surface, at least one axis of rotation,and a layer on the first surface, the layer including a variable meshpattern, wherein the variable mesh pattern comprises a plurality ofribs, the ribs having a first width near the at least one axis ofrotation and a second width at portions of the first surface fartherfrom the axis of rotation, the first width being greater than the secondwidth. The first width may taper to the second width. The layer may havea mass distributed across the first surface such that a center portionof the first surface bears a greater proportion of the mass as comparedto portions near the perimeter. The variable mesh pattern may be asymmetrical pattern. The plurality of ribs may be interconnected.

According to some examples, the component may be a mirror and the firstsurface is a backside non-reflective surface. The at least one axis ofrotation may extend across a center portion of the component, such thatthe first width of the ribs is near the center portion of the componentand the second width of the ribs is near one or more boundaries of theperimeter.

Another aspect of the disclosure provides a micro-electro-mechanicalsystems (MEMS) mirror assembly, including a plate including a pluralityof cavities, at least one mirror, the at least one mirror having areflector region rotatable about at least a first axis, the at least onemirror having a perimeter and a first surface, the at least one mirrorlocated within a respective one of the plurality of cavities. Thereflector region may include a layer on the first surface, the layerincluding a variable mesh pattern, wherein the variable mesh patterncomprises a plurality of ribs, the ribs having a first width near thefirst axis and a second width at portions of the first surface fartherfrom the first axis, the first width being greater than the secondwidth. The first width transitions to the second width. The transitionmay be a gradual taper. The layer may have a mass distributed across thefirst surface such that a center portion of the first surface bears agreater proportion of the mass as compared to portions near theperimeter. The variable mesh pattern may be a symmetrical pattern. Thereflector region of the at least one mirror may further be rotatableabout a second axis, and the ribs may have a greater width near thesecond axis as compared to near the perimeter.

Yet another aspect of the disclosure provides a method of fabricating aMEMS mirror, including applying a layer to a non-reflective surface of areflector region of the MEMS mirror, the reflector region defined by aperimeter, and forming a variable mesh pattern in the layer, wherein thevariable mesh pattern defines a plurality of ribs, the ribs having afirst width near a center of the reflector region and a second widthnear the perimeter, the first width being greater than the second width.Forming the variable mesh pattern may include removing at least aportion of the layer from the first surface to create the plurality ofribs. Removing a portion of the layer may include removing less than afull depth of the layer in a given area. In other examples, forming thevariable mesh pattern includes selectively depositing material onto thefirst surface in the variable mesh pattern.

The layer may have a mass distributed across the first surface such thata center portion of the first surface bears a greater proportion of themass as compared to portions near the perimeter. The variable meshpattern may be a symmetrical pattern, where each of the plurality ofribs are interconnected.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not intended to be drawn to scale. Likereference numbers and designations in the various drawings indicate likeelements. For purposes of clarity, not every component may be labeled inevery drawing. In the drawings:

FIG. 1 is a block diagram illustrating an OCS according to aspects ofthe disclosure.

FIG. 2 is an example MEMS mirror according to aspects of the disclosure.

FIG. 3 is an example die including an array of MEMS mirrors according toaspects of the disclosure.

FIG. 4 is an example data path and optical path of the optical coreaccording to aspects of the disclosure.

FIG. 5 is an example mirror control loop according to aspects of thedisclosure.

FIGS. 6A and 6B are examples of a portion of a MEMS mirror having atriangular pattern according to aspects of the disclosure.

FIG. 7A is an example of a portion of a MEMS mirror having a hexagonalpattern according to aspects of the disclosure.

FIG. 7B is an example of a portion of a MEMS mirror having a rectangularpattern according to aspects of the disclosure.

FIGS. 8A and 8B are examples of a portion of a MEMS mirror having a moreconcentrated mass near the center according to aspects of thedisclosure.

FIG. 9 is an example graph of the relative stiffness of a reflectorregion compared to the relative moment of inertia of the reflectorregion according to aspects of the disclosure.

FIG. 10 is an example component having a single axis of rotation andincluding a variable mesh pattern according to aspects of thedisclosure.

FIG. 11 is another example component having a single axis of rotationand including a variable mesh pattern according to aspects of thedisclosure

DETAILED DESCRIPTION

This disclosure generally relates to a component, such as a MEMS mirroror other generally disc-shaped component, having a variable mesh patternacross a backside surface of the mirror or other disc-shaped component.As such, the variable mesh pattern provides for increased relativestiffness of the mirror, as compared to a mirror supported by a uniformmesh or a solid layer, while decreasing the relative moment of inertiaof the mirror or other disc-shaped component. While the variable meshtechnique is described below in connection with MEMS mirrors and opticalnetwork systems, it should be understood that the variable meshtechniques may be applied in any of a number of different fields. By wayof example only, such techniques may be implemented intelecommunications, LIDAR, free space optical communications (FSOC),etc.

The component may have a perimeter and a first surface, such as abackside surface where the component is a mirror. A layer may be appliedto the first surface and a pattern may be etched into the layer, thepattern creating the variable mesh. According to other examples,material may be deposited onto the backside surface in an additiveprocess such that the deposited material forms the variable mesh.

The variable mesh pattern may define a plurality of ribs. The ribsclosest to the center may have a first thickness. The ribs closest tothe perimeter may have a second thickness. The first thickness may begreater than the second thickness. Thus, the ribs closest to the centermay be wider than the ribs closest to the perimeter. The ribs may taperor transition from the first thickness to the second thickness. Incontrast, a constant mesh may occur when a pattern is etched into thelayer such that the ribs defined by the pattern have an equal widththroughout the reflector region. A complete layer may be an un-etchedlayer applied continuously to the backside surface of the mirror.

The mirror or other disc-shaped component may be positioned in a deviceor system such that it is movable about one or more axes. For example,the mirror may be a MEMS mirror positioned in an optical signal routingsystem, and may be rotatable about an x axis and a y axis. The variablemesh on the backside surface of the MEMS mirror provides stiffness tothe mirror, thereby preventing the mirror from curling up or otherwisebecoming deformed. The variable mesh also improves the moment of inertiaabout the one or more axes.

FIG. 1 illustrates an example OCS 100, such as may be used indatacenter. The OCS 100 includes a structure such as chassis 110supporting a number of components. In front of the OCS chassis 110 areoptical fiber connections, such as fiber management block 120. The OCS100 may further include, such as in the middle, an optical core 130. Theoptical core houses MEMS 131, fiber collimators 134, optics 132, cameras135, and injectors 136 and other mechanisms 133. A rear of the OCS 100includes electronics 150, such as high voltage driver boards 152 for theMEMS, one or more processors 161, such as a CPU board, one or morememories 162 storing executable software, and power supplies 165 and fanmodules 166. The chassis 110 interfaces with OCS control system 160.While a number of components are shown, it should be understood thatsuch components are merely non-limiting examples, and that othercomponents may additionally or alternatively be included.

There may be any number of input fibers and output fibers connected tothe front of the OCS chassis 110. Inside the chassis 110, these fiberfanouts are spliced to the fiber collimators 134.

The fiber collimators 134 are lensed fiber arrays. Just as one example,the fiber collimators 134 may include tens or hundreds or more fiberarrays. The fibers are assembled in a hole array that matches a MEMSarray grid pattern. The fiber array is attached to a mounting flange. Alens array is aligned and attached to the fiber array. Fiber and lensposition errors are very tightly controlled.

FIG. 2 illustrates an example MEMS mirror 240. The MEMS mirror 240 mayvary in size, for example depending on implementation. By way of exampleonly, the MEMS mirror 240 may be between approximately several hundredmicrons and several hundred millimeters. The MEMS mirror 240 may behighly reflective. For example, the MEMS mirror 240 may be coated with ahighly reflective material, such as gold or other material. The mirror240 includes an inner portion 242 and an outer portion 244, wherein theinner portion is rotatable about a first axis and the outer portion isrotatable about a second axis. For example, the inner portion may rotateabout inner torsion beams 246 actuated by a comb drive actuator. Theouter portion may rotate about outer torsion beams 248 actuated by acomb drive actuator. The comb drive actuators may be high voltage,electro-static vertical comb drives which rotate the mirrors about thetorsion beams. For example, the rotation may be approximately between+/−1-10 degrees when a voltage ranging between tens of volts to hundredsof volts is applied across the electrodes.

FIG. 3 illustrates an example die including an array of MEMS mirrors240. According to some examples, the MEMS die packages include MEMSmirror arrays, but in other examples any number of MEMS mirrors may beincluded. The die may be hermetically sealed inside a package with awindow in its lid. Not all of the mirrors may be needed or used at thesame time. For example, only the best mirrors and fibers in a MEMSmirror array may be selected to make an optical switch, which may bedivided as a number of ports and a number of spares.

FIG. 4 provides an example of a data optical path and a monitor opticalpath included in the optical core. On data path 470, traffic comes in aslight input to fiber collimator A. All of the optics in the data path470 may be designed for very low loss over a variety of wavelengths. Thelight travels along this path 470, and is reflected from MEMSA, thenfrom MEMSB, then is coupled to output fiber collimator B. MEMS A andMEMS B may be just two MEMS mirrors of a larger array, such asillustrated in FIG. 3 and explained above. By rotating the mirrors inthe array, light from any input fiber can be coupled to any outputfiber. The injectors shine a plurality of small laser beams on the MEMS.The cameras image the beams reflected from the MEMS to measure themirror positions.

Monitor path 480 does not carry data, but provides information to amirror control system about the positions of the mirrors. This may bedone using, for example, an injector to shine small beams on each of theMEMS mirrors, and a camera to view the positions of the beams reflectedfrom the MEMS. There may be a camera/injector pair for each MEMS.

FIG. 5 illustrates an example mirror control loop. The OCS controlsystem 160 tells the OCS what configuration it should be in. The mirrorcontrol loop handles the MEMS mirror control and movement algorithmsbased on the monitor path data, and then tells the high voltage driversto move the mirrors.

FIG. 6A illustrates an example reflector region of a MEMS mirror. Thereflector region 600 may be the inner portion 242, as shown in FIG. 2 ,of MEMS mirror 240. In some examples, reflector region 600 may only be aportion of inner portion 242. Yet in other examples, the reflectorregion may be an outer portion 244 of MEMS mirror 240. Thus, thereflector region 600 may be located on any portion of the MEMS mirror.

Reflector region 600 may be defined by a perimeter 602. The perimeter602 of reflector region 600 may be a circle, square, hexagon, polygon,or any other shape.

A first surface of the reflector region 600 may be the non-reflective,backside surface. A second surface, opposite the first surface, may bethe reflective surface.

The first surface of reflector region 600 may include a layer 608. Thelayer 608 may be a solid piece of silicon, nitrite, poly-silicon or anyother suitable material. The layer 608 may be etched, thereby creating apattern in the remaining portions of the layer 608. In some examples,the layer 608 may be applied or deposited in the desired pattern. Layer608 may influence the radius of curvature of reflector region 600. Thepattern of layer 608 reduces a mass of the mirror as compared to havinga solid layer or a patterned layer with uniform width, and also impactsthe moment of inertia of the MEMS mirror, which may allow the MEMSmirror to be rotated more easily.

The second surface of the reflector region may include the reflectivesurface. For example, the second surface may include solid silicon orother material. According to other examples, the second surface mayinclude a highly reflective coating, such as chrome, gold, aluminum,dielectrics, or other materials. The materials for the reflectivesurface may be selected based on the intended use case, wavelengthrange, or other factors.

Layer 608 may provide a degree of stiffness to the MEMS mirror. MEMSmirrors without layer 608 may deform in shape. For example, the MEMSmirror may curl, such as due to the stress on the material. Therefore,applying layer 608 may increase the stiffness of the MEMS mirror toprevent the deformation of the MEMS mirror.

Layer 608 may begin as a solid or complete layer and be etched into thepattern shown in FIG. 6A or any other variable mesh pattern, severalnon-limiting examples of which are illustrated in the following figures.As shown in FIGS. 6A and 6B, the pattern may be triangular. As shown, aplurality of triangles may radiate outwardly from a center 612 of thebackside of the reflector region 600. Open areas 606 may be thetriangles, for example, that were etched away. In such examples, theopen areas may be completely etched, such as to remove an entire depthof the material of the layer 608 in the area. In other examples, theopen areas may be etched such that a percentage of the depth of thematerial is removed, while leaving in that area some material of ashallower depth as compared to the original layer. The pattern may besymmetrical. For example, pattern may be symmetrical about a diameter ofthe reflector region 600. While this pattern is described in thisexample as being etched from a solid layer, it should be understood thatin other examples the same pattern may be formed by depositing materialin the formation of the pattern onto the backside of the reflectorregion. According to some examples, there may not be a rib 610 aroundperimeter 602, while in other examples (not shown), there may be a ribaround the perimeter 602.

FIG. 6B shows a zoomed-in portion of the pattern shown in FIG. 6A. Thepattern may include a plurality of ribs 610. A rib 610 may be locatedbetween each of the open areas 606. Thus, the rib 610 may be the portionof layer 608 that remains on the backside of the reflector region 600.

The ribs 610 may vary in width. For example, referring back to FIG. 6A,ribs 610 may taper from a first width at the center 612 of reflectorregion 600 to a second width at the perimeter 602, wherein the firstwidth is greater than the second width. The taper may be a gradual andconsistent transition from the first width to the second width. Thewidest portion of the taper may be closest to the center 612. Thus, thewidest ribs 610 may be located closest to the center 612 of reflectorregion 600. According to some examples, where the widest portion ofmultiple ribs intersect at the center 612, an area immediatelysurrounding the center 612 may be continuously covered by material.

The narrowest portion of the taper may be closest to the perimeter 602.The tapering of ribs 610 may create a variable mesh on reflector region600. The variable mesh pattern may have variable spacing between openareas 606.

In contrast, a constant mesh may be a pattern that has equal spacingbetween each etched area. The constant mesh may include ribs of the samewidth throughout the pattern. Thus, the mass of the layer in theconstant mesh may be distributed equally across the backside surface ofthe reflector region.

The mass of layer 608 that remains on the backside surface of thereflector region 600 after the pattern is formed may be distributedacross the surface such that a greater mass is concentrated toward thecenter of the reflector region 600 as compared to portions of thereflection region near the perimeter. For example, a portion of thepattern closest to the center 612 may have more mass due to the widestribs 610 as compared to the portion closest to the perimeter 602 whichhas the narrowest ribs 610. Concentrating the mass of layer 608 near thecenter 612 of reflector region 600 may result in a smaller moment ofinertia of the reflector region 600 as compared to a reflective portion600 having an equally distributed layer. Thus, the width of the ribs610, and their corresponding mass, may impact the relative moment ofinertia of the reflector region 600.

The relative moment of inertia may impact how long it takes the MEMsmirror to move, the shock felt by the MEMS mirror, and/or the MEMSmirror's resistance to vibration. The relative stiffness provided by theetched pattern may allow for the MEMS mirror to experience highresonance frequencies. The relative stiffness may also keep thereflective surface 600 and/or the MEMS mirror flat.

The width of ribs 610 may also determine the relative stiffness of thereflector region 600. The relative stiffness of reflector region 600 maybe relative as compared to a reflector region without a patternedbackside surface.

FIG. 7A illustrates an example backside surface of a reflector region ofa MEMS mirror. Reflector region 700 is substantially similar to thereflector region 600 described with respect to FIGS. 6A and 6B and,therefore, has substantially corresponding reference numbers. As shown,reflector region 700 may be defined by a perimeter 702. The perimetermay or may not include a rib extending around the perimeter. A patternedlayer 708 may be applied to a first surface, such as a backsidenon-reflective surface, of the reflector region 700. The layer 708 maybe formed by etching a solid layer or by depositing material in theformation of the pattern. As shown in this example, the pattern 704 mayinclude a plurality of hexagons distributed across reflector region 700.According to other examples, the pattern may include a plurality ofsquares, diamonds, circles, polygons, or any other shape.

According to some examples, the pattern on the backside surface of thereflector region may be symmetrical. In such an example, thedistribution of mass across reflector region 700 may be symmetrical.Having symmetrically distributed mass may balance the reflector region700 and, therefore, the MEMS mirrors. The MEMS mirrors may, therefore,rotate accurately and uniformly, without wobbling, unintentionallyrotating, or resting in an undesirable position.

Similar to the example described above in connection with FIGS. 6A-B, inFIG. 7A the pattern may include a plurality of ribs 710 that may belocated between each open area 706, where a thickness of the ribs 710near a center portion 712 is greater than the thickness of the ribs 710near the perimeter 702. The ribs 710 may transition from the thickestportions of the ribs 710 located near the center 712 to the thinnestportions of the ribs 710 near the perimeter 702. The transition of ribs710 may create a variable mesh. In some examples, the transition may bea gradual taper. In other examples, the transition may be a non-gradualchange in width. For example, the transition may be a step-liketransition. In such an example, a series of steps may be defined betweenthe center portion 712 and the perimeter, where the thickness of a givenrib decreases each step as it extends from the center to the perimeter.The variable mesh created by pattern 704 may result in a greater massnear center 712 of reflector region 700 as compared to near theperimeter 702.

FIG. 7B illustrates another example pattern for the variable mesh. Inthis example, open areas 726 may be square or rectangular shaped, withribs 730 extending between the open areas 726. The ribs 730 near acenter portion of the mirror are generally wider or greater than atportions near the perimeter. In some examples, a size of the open areas726 may increase from a first size towards the center of the mirror to asecond larger size towards the perimeter of the mirror. The ribs 730 maytransition in thickness from the center towards the perimeter, which maybe a gradual and consistent transition or a more distinct or step-wisetransition. The size and/or distribution of the open areas 726 may alsogradually transition. It should be understood that this is merely oneexample, and that the size, spacing, and distribution of the open areas726 may be modified. Moreover, while the examples provide patterns withconsistent shapes, such as all triangles, hexagons, rectangles, etc., itshould be understood that multiple shapes may be used within the samepattern.

FIGS. 8A and 8B illustrate another example variable mesh pattern thatmay be formed on the non-reflective or backside surface of a mirror orother disc-shaped component. Reflector region 800 is substantiallysimilar to the reflector region 600, 700 described with respect to FIGS.6A-B, and 7A and, therefore, has substantially corresponding referencenumbers. As shown, reflector region 800 has a similar pattern asreflector region 600, except the center of the reflector region 800includes more continuously solid area as compared to the region 600. Forexample, a layer of material forming the ribs 810 and pattern may not beetched in the area closest to the center 812. Thus, more mass may belocated near the center 812 of reflector region 800 than near theperimeter 802 of reflector region 800.

FIG. 8B shows a perspective view of reflector region 800. In thisexample, the perimeter 802 is not defined by a rib. Ribs 810 may beraised from the surface of reflector region 800. According to someexamples, ribs 810 may be the remaining material after a pattern hasbeen etched in a solid layer. In other examples, the ribs 810 may beformed by selectively depositing material. Ribs 810 may be widest nearcenter 812 of reflector region 800, and may gradually taper to a thinnerrib 810 near perimeter 802.

FIG. 9 illustrates an example graph plotting relative stiffness of thereflector region as compared to the relative moment of inertia of thereflector region. A reflector region with none of the layer etched wasused as a comparison for all the tests. Thus, the reflector region withnone of the layer etched has a relative stiffness of 1.0 and a relativemoment of inertia of 1.0, as shown by point 912 on graph 900. All thetests were based on a specific overall plate thickness. For example, theplate thickness may be 25T. The layer may have a thickness of 20 um,such that the etch depth may be 20 um to remove the layer. There mayalso be a specific beam separation value for each test. The beam widthmay be varied.

Curve 914 may fit data plotting stiffness vs. moment of inertia for aplurality of mirrors or other components, represented by points 902-912.Each of these mirrors or other components includes a continuoussupporting backside surface layer, or a uniform constant mesh where ribshave the same thickness throughout.

The curve 914 indicates a proportionality between stiffness and relativemoment of inertia for a MEMS mirror having a constant or non-variedmesh. As the relative stiffness increases, the relative moment ofinertia may increase. The relative stiffness and/or the relative momentof inertia may be based on the mass of the reflector region. Thus, asthe mass increases, the relative stiffness and/or the relative moment ofinertia increases.

In contrast, data points 916 and 918 may represent the relativestiffness and moment of inertia for mirrors having a variable mesh. Line916 may provide for comparison between point 910 and point 920. Forexample, while the two points indicate mirrors or other disc-shapedcomponents having a same relative stiffness. the variable mesh design ofthe mirror corresponding to point 920 results in a lower moment ofinertia. The variable mesh reflector regions may have an increasedrelative stiffness while also having a lower relative moment of inertia,as compared to the constant mesh reflector regions.

While a number of example mirror shapes and mesh patterns have beendescribed above, it should be understood that additional shapes and/orvariable patterns are possible. For example, the mirrors may be square,rectangular, oval, octagonal, etc. The mirrors may have a single axis ofrotation or additional axes. Moreover, the mirrors may vary in size. Forexample, the variable mesh patterns may be applied to mirrors of verysmall size for some applications or of much larger sizes for otherapplications.

FIG. 10 illustrates an example MEMS mirror 1000 having a rectangular orsquare shape. The MEMS mirror 1000 may be defined by a perimeter 1002.On a first surface, such as a non-reflective surface, a layer 1008 maybe applied. The layer 1008 may be silicon, nitrite, poly-silicon or anyother suitable material. The layer 1008 may be etched or otherwiseformed into a pattern. In some examples, the layer 1008 may be appliedto the first surface in the desired pattern.

As shown in FIG. 10 , the pattern may be a striped pattern. Thus, layer1008 may be etched in lines or stripes parallel or substantiallyparallel to an axis 1012 of reflector region 1000. Lines or areas 1006may be etched portions of layer 1008. Ribs 1010 may be lines or areas oflayer 1008 that remain after layer 1008 is etched. Ribs 1010 may have agreater width closer to the axis 1012 of reflector region 1000. Thewidth of each rib 1010 may decrease as the distance from axis 1012increases. Thus, more mass may be located near axis 1012 than near atleast a portion of perimeter 1002.

FIG. 11 illustrates another example of a MEMS mirror 1100 having arectangular or square shape. The MEMS mirror 1100 may be similar to MEMSmirror 1000 shown in FIG. 10 and, therefore, may have correspondingreference numbers. MEMS mirror 1100 may be defined by a perimeter 1102.A layer 1108 may be applied to or otherwise formed on a first surface,such as a non-reflective surface, of the MEMS mirror 1100. The layer1108 may be applied in a pattern. In some examples, a pattern may beetched into layer 1108.

As shown in FIG. 11 , the pattern may include a plurality of triangularribs 1110. The pattern may be etched into layer 1108 such that openareas 1106 are etched away or are kept open when depositing material,and triangular ribs 1110 and horizontal ribs 1111 are formed bysupportive material. Triangular ribs 1110 may have a larger width nearaxis 1112 as compared to the width of the triangular ribs 1110 near anupper or lower boundary of the mirror. For example, the ribs, ortriangles 1110, may taper to a narrower width near perimeter 1102. Thus,more mass may be located nearest axis 1112.

An example method of manufacture of the reflector region may includeapplying a layer to a first surface of the reflector region of a MEMSmirror. The first surface may be, for example, a backside ornon-reflective surface of the mirror. The reflector region may bedefined by a perimeter, which may encompass a portion of the mirror oran entirety of the mirror. The layer may be applied as a continuouslayer of material, in which case the method may further include etchinga variable mesh pattern into the layer. Etching the pattern may includeremoving at least a portion of the layer from the surface. Removing atleast a portion of the layer may create a plurality of ribs. The removedor etched portions of the pattern may be a shape. According to someexamples, the shapes may be triangular, rectangular, hexagonal,circular, etc. The etched pattern may be symmetrical. According to otherexamples, the layer may be formed by depositing material onto the firstsurface in the variable mesh pattern.

The variable mesh pattern may define a plurality of ribs. The ribsclosest to the center of the reflector region may have a first width.The ribs closest to the perimeter of the reflector region may have asecond width. The first width may be greater than the second width suchthat the ribs closest to the center may be wider than the ribs closestto the perimeter. The ribs may be interconnected. The ribs may taperfrom the first width to the second width. In some examples, the ribs maysmoothly and gradually transition from the first width to the secondwidth. In other examples, the transition may include more defined ordiscrete variations or steps in width.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyinventions or of what may be claimed, but rather as descriptions offeatures specific to particular implementations of particularinventions. Certain features that are described in this specification inthe context of separate implementations can also be implemented incombination in a single implementation. Conversely, various featuresthat are described in the context of a single implementation can also beimplemented in multiple implementations separately or in any suitablesub-combination. For example, while the variable mesh technique isgenerally described in connection with MEMS mirrors and optical networksystems, it should be understood that the variable mesh techniques maybe applied in any of a number of different fields. By way of exampleonly, such techniques may be implemented in telecommunications, LIDAR,free space optical communications (FSOC), etc.

Moreover, although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asub-combination or variation of a sub-combination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various systemcomponents in the implementations described above should not beunderstood as requiring such separation in all implementations, and itshould be understood that the described program components and systemscan generally be integrated together in a single software product orpackaged into multiple software products.

References to “or” may be construed as inclusive so that any termsdescribed using “or” may indicate any of a single, more than one, andall of the described terms. The labels “first,” “second,” “third,” andso forth are not necessarily meant to indicate an ordering and aregenerally used merely to distinguish between like or similar items orelements.

Various modifications to the implementations described in thisdisclosure may be readily apparent to those skilled in the art, and thegeneric principles defined herein may be applied to otherimplementations without departing from the spirit or scope of thisdisclosure. Thus, the claims are not intended to be limited to theimplementations shown herein, but are to be accorded the widest scopeconsistent with this disclosure, the principles and the novel featuresdisclosed herein.

What is claimed is:
 1. A component, comprising: a region having aperimeter and a first surface; at least a first axis of rotation and asecond axis of rotation; a layer on the first surface, the layerincluding a variable mesh pattern, wherein the variable mesh patterncomprises a plurality of ribs, the ribs having a first width near thefirst axis of rotation and a second width at portions of the firstsurface farther from the first axis of rotation, the first width beinggreater than the second width, wherein the ribs have a greater widthnear the second axis as compared to near the perimeter.
 2. The componentof claim 1, wherein the first width tapers to the second width.
 3. Thecomponent of claim 1, wherein the layer has a mass distributed acrossthe first surface such that a center portion of the first surface bearsa greater proportion of the mass as compared to portions near theperimeter.
 4. The component of claim 1, wherein the variable meshpattern is a symmetrical pattern.
 5. The component of claim 1, whereinthe plurality of ribs are interconnected.
 6. The component of claim 1,wherein the component is a mirror and the first surface is a backsidenon-reflective surface.
 7. The component of claim 1, wherein the firstaxis of rotation extends across a center portion of the component, suchthat the first width of the ribs is near the center portion of thecomponent and the second width of the ribs is near one or moreboundaries of the perimeter.
 8. A micro-electro-mechanical systems(MEMS) mirror assembly, comprising, a plate including a plurality ofcavities; at least one mirror, the at least one mirror having areflector region rotatable about a first axis of rotation and a secondaxis of rotation, the at least one mirror having a perimeter and a firstsurface, the at least one mirror located within a respective one of theplurality of cavities, wherein the reflector region includes: a layer onthe first surface, the layer including a variable mesh pattern, whereinthe variable mesh pattern comprises a plurality of ribs, the ribs havinga first width near the first axis of rotation and a second width atportions of the first surface farther from the first axis, the firstwidth being greater than the second width, wherein the ribs have agreater width near the second axis as compared to near the perimeter. 9.The MEMS assembly of claim 8, wherein the first width transitions to thesecond width.
 10. The MEMS assembly of claim 9, wherein the transitioncomprises a gradual taper.
 11. The MEMS assembly of claim 8, wherein thelayer has a mass distributed across the first surface such that a centerportion of the first surface bears a greater proportion of the mass ascompared to portions near the perimeter.
 12. The MEMS assembly of claim8, wherein the variable mesh pattern is a symmetrical pattern.
 13. Amethod, comprising: applying a layer to a non-reflective surface of areflector region of a micro-electro-mechanical systems (MEMS) mirrorhaving a first axis of rotation and a second axis of rotation, thereflector region defined by a perimeter; and forming a variable meshpattern in the layer, wherein the variable mesh pattern defines aplurality of ribs, the ribs having a first width near the first axis ofrotation region and a second width near the perimeter, the first widthbeing greater than the second width, wherein the plurality of ribs havea greater width near the second axis as compared to near the perimeter.14. The method of claim 13, wherein forming the variable mesh patterncomprises removing at least a portion of the layer from the firstsurface to create the plurality of ribs.
 15. The method of claim 14,wherein removing a portion of the layer comprises removing less than afull depth of the layer in a given area.
 16. The method of claim 13,wherein forming the variable mesh pattern comprises selectivelydepositing material onto the first surface in the variable mesh pattern.17. The method of claim 13, wherein the layer has a mass distributedacross the first surface such that a center portion of the first surfacebears a greater proportion of the mass as compared to portions near theperimeter.
 18. The method of claim 13, wherein the variable mesh patternis a symmetrical pattern.
 19. The method of claim 13, wherein each ofthe plurality of ribs are interconnected.